Muffler



Deg. 5, 1939.

Q. G. NOBLITT ET AL 2,182,405

MUFFLER Filed Nov. '5, 1938 2 Sheets-Sheet 1 INVENTORS, Qw/Vr/NJ. A251 07 and Dec. 5, 1939.

Q. G. NOBLITT ET AL 2,182,405

MUFFLER 2 Sheets-Sheet 2 Filed Nov. 5, 1938 INVENTORS, QU/lYiV/Y 601/05 4 7'7 a/za' BY A o a/Y0 Zamazr "W Z r ATTORNEYS Patented Dec. 5, 1939 UNITED STATES PATENT OFFICE MUFFLER Indiana Application November 5, 1938, Serial No. 238,983

7 Claims.

Our invention relates to mufilers for silencing the exhaust of internal-combustion engines and has for its object the production of a mufiler which will adequately silence the exhaust, which will be simple in construction and relatively light in weight, and which lends itself to economical production in large quantities. A further object of our invention is to reduce the quantity of moisture which condenses within the mufiler and which has a tendency to rust and corrode the material of which the muffler is made.

In carrying out our invention, we provide a cylindrical mufiler shell with end heads and with transverse partitions defining a pair of axially spaced expansion chambers. Within each expansion chamber there is located a pair of axially extending silencing tubes; and transverse passages are arranged so that an unrestricted retroverted main gas-passage is provided including, in series, the four silencing tubes and the two expansion chambers themselves. Within the expansion chamber, each silencing tube is provided with a multiplicity of restricted openings through which gases may flow from the tube into the associated silencing chamber, and vice versa.

The accompanying drawings illustrate our invention: Fig. 1 is an axial section through a mufiler on the broken line of Fig. 2; Fig. 2 is an end elevation of the muffler shown in Fig. 1; Fig. 3 is a diagrammatic developed View of the mufiler shown in Figs. 1 and 2, illustrating the flow of gases therethrough; and Fig. 4 is a view similar to Fig. 3 but illustrating a modified arrangement.

The muffler shown comprises a cylindrical shell Ill and heads I and 2 located respectively at the inlet and discharge ends of the mufiier. Near the inlet end of the mufller are a pair of spaced transverse partitions l3 and I4 defining between them an expansion chamber I5. A similar pair of partitions l6 and I1 located in axially spaced relation near the discharge end of the muffler define a second expansion chamber IS. The two partitions I4 and H5 at the inner ends of the expansion chambers are spaced apart, and in the interval between them there is disposed an auxiliary transverse partition 20 which defines, in co-operation respectively with the partitions I4 and I6, two transverse gas passages 2| and 22. The partitions I3 and I1 near the ends of the mufiler are spaced from the heads II and I2 to define additional transverse passages 23 and 24 respectively.

Extending axially through the expansion chamber |5 are two silencing tubes 26 and 21. A similar pair of silencing tubes 28 and 29 extend axially through the second expansion chamber l8. Each of the tubes 26 to 29 inclusive is provided with a multiplicity of restricted openings, conveniently formed by providing the tube-wall with axially spaced, circumferentially extending slits and by bending the material of the tube-wall outwardly at one side of each slit to form louvers 30.

In the arrangement illustrated in Figs. 1 to 3 inclusive the two partitions l3 and M are provided with alined openings 32 and 33 affording communication between the expansion chamber l5 and the passages 23 and 2| respectively. A similar pair of alined openings 34 and 35 in the partitions Hi and I1 afford communication between the chamber 8 and the passages 22 and 24 respectively. The two silencing tubes 21 and 2B are interconnected by a pair of telescoping nipples 36 and 31 one of which, here shown as the nipple 36, extends through the auxiliary partition 20.

The tubes 26 and 21 and the pair of alined openings 32 and 33 are conveniently arranged at equal angular intervals about the axis of the shell ID. A similar arrangement may be followed in the disposition of the tubes 28 and 29 and the pair of alined openings 34 and 35.

In the head II and communicating with the silencing tube 26 there is mounted an inlet fitting 40 adapted for connection to the exhaust pipe leading from the engine whose exhaust is to be silenced. In the head |2 we mount a nipple 4| communicating with the tube 251. The nipple 4| may be adapted for connection to a tail pipe, or may be formed as the tail pipe itself.

In the muffier shown in Figs. 1 to 3 inclusive, the gases enter the muffler through the nipple 40 and pass directly into the first silencing tube 26. The main path of gas flow is through the tube 26, passage 2|, tube 21, passage 23, tube 21, nipples 36 and 31, tube 28, passage 24, opening 35, chamber l8, opening 34, passage 22, and tube 29 into the discharge nipple or tail pipe 4|. The openings 32, 33, 34, and 35, and the passages 2|, 22, 23, and 24 all possess cross-sectional dimensions providing an area at least equal to the cross-sectional area of the tubes 26 to 29 inclusive, so that the main path of gas-flow above described presents no restrictions.

Gas flow is not confined to the main path above described; for some of the gases will escape through the louvers 30 in the tube 26 into the expansion chamber, and some gases will enter the louvers in the tube 21 from the expansion chamber. Similar possibilities of auxiliary gas flow are provided by the louvers in the tubes 28 and 29. We have found it of some advantage to slope the louvers 3B in each tube to favor the flow of gas through the louvers. Thus, the louvers of the tubes 26 and 28, through which gases flow outwardly, are sloped outwardly toward the rear or discharge end of the mufiler, while the louvers on the tubes 2'! and 29 slope in the opposite direction.

If desired, certain of the transverse partitions within the shell, here shown as the partitions M, 25, and it, may be provided with restricted openings Q3. The presence of such openings tends to decrease the back-pressure for which the mufiier is responsible; but they also tend to decrease silencing efficiency. They should therefore be used judiciously, if at all.

In the muffler shown in Fig. 4, we have rearranged the openings 32, 33, 34, and 35 so that they are all in line with each other. We have also rearranged the nipples 36 and 31 so that they interconnect the two openings 33 and 34, thus leaving the rear end of the tube 2'! communicating with the passage 2i and the front end of the tube 28 communicating with the passage 22. Ihe silencing action and the flow of gases is much the same, the only difference being that in the main path of gas-flow the two silencing tubes of each expansion chamber are arranged in direct succession instead of being separated by the passage of the gases through the expansion chamber itself.

As to constructional details, the various transverse partitions are formed with peripheral shellfitting flanges. In addition, the material at the edge of each main opening in such partitions is formed into a short annular flange. In the case of those partition-openings which receive silencing tubes, such flanges provide supports for the ends of the silencing tubes and may be tackwelded thereto. In the case of the openings 32 to 35 inclusive, none of which receives a silencing tube, the flanges tend to reduce loss of head in the gases flowing through the openings, stifien the partition, and make a more durable construction.

In making the muffler, the shell it is first formed and the auxiliary partition 20 secured in place therein by welding its peripheral flange to the shell. The two partitions l3 and M, the two silencing tubes 26 and 21, and the two nipples 36 and ii? are put together as a sub-assembly, the ends of the silencing tubes being tackwelded to the partitions and the nipples being butt-welded to the proper tubes or to flanges on the partitions. The partitions I 8 and H, the silencing tubes 28 and 29, and the nipples 31 and iii are similarly put together as a second subassembly. The two sub-assemblies are then slid into the shell from opposite ends, the nipple 36 passing through the auxiliary partition 20 and entering the enlarged inner end of the nipple 3?. The sub-assemblies are then secured in place by welding the peripheral flanges on the partitions l3 and Il to the shell. To facilitate this welding operation, the peripheral flanges on the partitions i3 and iii are directed toward the adjacent end of the shell. Conveniently, the flanges I on the partitions i l and it are similarly directed,

such clearances being allowed as are required to compensate for unavoidable variations in dimensions.

After the two sub-assemblies are secured in place on opposite sides of the auxiliary partition 20, the heads H and I2 are placed on the shell and secured thereto, preferably through the use of lock-seams such as are indicated at 45. The edges of the nipple-receiving openings in the heads ii and N. are desirably flanged outwardly; and after the heads are in place, the joints between the nipples and the respective heads are sealed by welding.

By including each of the expansion chambers i6 and iii in the main gas passage, a substantial flow of exhaust gases through those chambers is insured. This circulation tends to prevent the accumulation of condensed moisture within the expansion chambers and thereby reduce rust and corrosion of the material of which the mufiier is formed.

We claim as our invention:

1. In a muiiler, a shell having end heads, transverse partitions providing within said shell two axially spaced expansion chambers and also a transverse gas passage at each end of each of said expansion chambers, 21. silencing tube extending axially through each of said expansion chambers, a nipple communicating with the outer end of each of said silencing tubes and extending through the adjacent head, the inner end of each of said silencing tubes communicating with the transverse passage at the inner end of the associated expansion chamber, a second silencing tube extending axially through each expansion chamber and having its outer end communicating with the transverse passage at the outer end of the associated expansion chamber, each of said silencing tubes having within its associated expansion chamber a multiplicity of restricted openings, the partitions deflning the ends of said expansion chambers being provided with openings aflording communication between the chamber and the adjacent transverse passages, and a conduit interconnecting the inner ends of said second silencing tubes.

2. In a muifier, a shell, transverse partitions providing within said shell two axially spaced expansion chambers, two silencing tubes extending axially through each of said chambers, each of said silencing tubes having within its associated expansion chamber a multiplicity of restricted openings, and means associated} with said shell and defining transverse passages interconnecting said tubes and chambers in series to form a substantially unrestricted, retroverted main gas passage.

3. In a muffler, a shell having end heads, trans- Verse partitions providing within said shell two axially spaced expansion chambers and also a transverse gas passage at each end of each of said expansion chambers, a silencing tube extending axially through each of said expansion chambers, a nipple communicating with the outer end of each of said silencing tubes and extending through the adjacent head, the inner end of each of said silencing tubes communicating with the transverse passage at the inner end of the associated expansion chamber, a second silencing tube extending axially through each expansion chamber and interconnecting the transverse passages at the ends of the associated expansion chamber, each of said silencing tubes having within its associated expansion chamber a multiplicity of restricted openings, the partition defining the outer end of each expansion chamber being provided with an opening afiording communication between the expansion chamber and the adjacent transverse passage, and a conduit interconnecting the inner ends of said two expansion chambers.

4. in a mufiler, a shell, two axially spaced transverse partitions defining an expansion chamber Within said shell, two silencing tubes extending axially through said expansion chamber, each of said silencing tubes having within said chamher a multiplicity of restricted openings, and means associated with said shell and defining transverse past-ages interconnecting said tubes and said chamber in series to form a substantially unrestricted, retroverted main gas passage.

5. In a mufiier, a shell, a transverse partition secured Within said shell intermediate the ends thereof, a sub-assembly disposed within said shell on each side of said partition, each of said subassernblies including at least one shell-fitting partition and at least one silencing tube secured thereto, each of said sub-assemblies also including at its inner end a nipple rigidly secured to the remainder of the sub-assembly, said first named partition being provided with an opening, said nipples and opening being disposed in alinement, one of said nipples having a slip fit within said opening and extending therethrough and being telescopically received within the other nipple.

6. In a muffler, a shell, a transverse partition Within said shell, a tubular gas-conveying member extending longitudinally of said shell and supported at least in part by said partition, a sub-assembly Within said shell comprising a plurality of silencing tubes with perforated walls and second and third transverse partitions, said second and third transverse partitions being spaced axially of said silencing tubes and secured thereto to form a unitary structure, one of said silencing tubes extending through one of its as sociated partitions and being telescopically and slidably associated with said tubular member.

'7. The invention set forth in claim 6 with the addition that said tubular member extends through the partition which partially supports it.

QUINTIN G. NOBLITT. EDMUND LUDLOW. 

